The magpie-sized Archaeopteryx had bird and dinosaur features and helped show that birds evolved from dinosaurs. However, recent research in the journal Nature questions its position in the dinosaur-bird family tree.

They are lightweight and yet strong and resilient: straw, bamboo, bones and teeth owe their surprising strength to their cleverly designed internal structures and a judicious combination of materials. The same principles ...

(PhysOrg.com) -- A 15 year old British girl, Chloe Holmes, has been in the news as being among the youngest in Europe to wear a special prosthetic hand with state of the art bionic fingers. The bionic digits have enabled ...

(PhysOrg.com) -- In what is believed to be a gravesite filled with thousand year old Viking bodies along with separated heads, in southern Britain, a new artifact has been discovered; one of the slain Vikings had his two ...

(PhysOrg.com) -- Tiny fossil teeth discovered in Inner Mongolia are a new species of birch mouse, indicating that ancestors of the small rodent are much older than previously reported, according to paleontologist Yuri Kimura, ...

(PhysOrg.com) -- Canadian Louise Page, associate professor at the University of Victoria, BC, has solved a mystery that has perplexed zoologists since early 19th century naturalists first wondered if venomous cone snails ...

A fang-like tooth on double upper lips, spiny teeth on the tongue and a pulley-like mechanism to move the tongue backwards and forwards -- this bizarre bite belongs to a conodont and, thanks to fresh fossil finds, has now ...

Tooth

Teeth (singular tooth) are small whitish structures found in the jaws (or mouths) of many vertebrates that are used to tear, scrape, and chew food. Some animals, particularly carnivores, also use teeth for hunting or defense. The roots of teeth are covered by gums. Teeth are not made of bone, but rather of tissues of varying density and hardness.

Teeth are among the most distinctive (and long-lasting) features of mammal species. Paleontologists use teeth to identify fossil species and determine their relationships. The shape of the animal's teeth are related to its diet. For example, plant matter is hard to digest, so herbivores have many molars for chewing. Carnivores, on the other hand, need canines to kill prey and to tear meat.

Mammals are diphyodont, meaning that they develop two sets of teeth. In humans, the first set (the "baby," "milk," "primary" or "deciduous" set) normally starts to appear at about six months of age, although some babies are born with one or more visible teeth, known as neonatal teeth. Normal tooth eruption at about six months is known as teething and can be painful.

Some animals develop only one set of teeth (monophyodont) while others develop many sets (polyphyodont). Sharks, for example, grow a new set of teeth every two weeks to replace worn teeth. Rodent incisors grow and wear away continually through gnawing, maintaining relatively constant length. Many rodents such as voles (but not mice) and guinea pigs, as well as rabbits, have continuously growing molars in addition to incisors.